DC insulating properties of newly developed XLPE cable

We have conducted a study into the application of high density polyethylene (HDPE) to DC cable insulation. HDPE has excellent electrical properties under DC voltage. However, it appeared that HDPE is very difficult to use for DC cable insulation because of a production problem where HDPE easily generates voids, in which case the insulation wall thickness increases. We studied past experimental knowledge again, and investigated the development of new DC power cable insulation.